The 1990s were heralded as the decade of the mouse. As the new century approaches, the mouse appears to be an even greater biomedical tool. A limiting factor is not the means to generate new mutations or find spontaneous ones, rather it is the expertise needed to critically evaluate these animals and interpret their lesions with comparison to human diseases. This midcareer award takes advantage of the unique resources of mice and focused scientists at The Jackson laboratory and particularly the experience and expertise of Dr. John Sundberg, the staff pathologist for over 12 years, to train the new generation of comparative pathologists and biomedical researchers in this area. A variety of perfected personalized training methods for long and short term visits by investigators will be used to teach basic mouse pathobiology and methodology. A small research project focused on the pathobiology of the spontaneous lanceolate hair mouse mutation will include high resolution mapping of the mutant gene locus with candidate gene screening in both mutant mice and humans with an homologous disease to be used as a training aid.